A growing number of teens and young children are presenting to U.S. emergency rooms with signs of opioid addiction or dependency, according to the findings of new research.

More than 100 youths test positive for opioid problems every day in emergency rooms across the United States, according to a study that will be presented today at the American Academy of Pediatrics (AAP) 2017 National Conference & Exhibition in Chicago.

The study was conducted by researchers from the University of Iowa Stead Family Children’s Hospital, involving a retrospective analysis of the 2008-2013 data fro m the Nationwide Emergency Department Sample, which is the largest all-payer ER database in the United States.

Researchers examined records of children and teens who came into the ER for any reason and whose doctor had a suspicion to test for opioids, indicating that the number of youth who were diagnosed with problems from opioid drugs, such as dependency or addiction to narcotic painkillers, increased from 32,000 in 2008 nearly 50,000 by 2013. The results are considered preliminary until published in a peer reviewed journal, but add to the mounting concerns about the opioid abuse epidemic in the U.S.

“It was very concerning to see that by the last year we studied, an average of 135 children each day were testing positive for opioid addiction or dependency in emergency departments,” Dr. Veerajalandhar Allareddy, one of the study’s authors and medical director of the pediatric intensive care unit at the University of Iowa Stead Family Children’s Hospital, said in an AAP press release. “In our opinion, this is a pediatric public health crisis.”

Nearly 88% of the youth who tested positive for opioid abuse were between 18 and 21 years old. About 8% were 16 and 17 year olds. Researchers said only a “handful of cases” involved children younger than 12 years old.

About one-third of youth in the new study were admitted as inpatients, regardless of cause, to the same hospital as the initial ER visit. Overall, pediatric patients living in high-income households were more likely to be hospitalized, rather than routinely discharged. This was compared to uninsured patients, who were less likely to be hospitalized for their addiction.

Study authors said the income-based difference is one of the many reasons youth opioid addiction requires further study.

Researchers warn the latest data only represents the youth who ended up in the emergency room, not every teen affected by narcotic painkiller addictions.

“This was intended to be an exploratory study,” Allareddy said. ”one that we hope will help alert the public, researchers, and policymakers of the need to fully define and address this important, emerging public health problem among children in the United States.”